Photodynamic therapy (PDT) is a modality that uses a photosensitizing agent and laser light to create oxygen radicals resulting in the destruction of cancer cells and bacteria. As this modality destroys bacteria via a different mechanism than antibiotics, its effectiveness is not altered by bacteria that have antibiotic resistance. Recently, there has been a rapid increase in the strains of antibiotic resistant bacteria with over 90% of Staphylococcus aureus strains being methicillin resistant. These bacteria have resulted in an inability to adequately treat common wound infections with antibiotics causing morbidity and death. PDT destruction of antibiotic resistant Staphylococcus aureus in vivo and antibiotic resistant Streptococcus pyogenes and Pseudomonas aeruginosa in vitro has been demonstrated using methylene blue. The proposed research will evaluate the use of methylene blue with 664 nm laser light as an improved device and dye combination for the efficacious treatment of infected surface wounds. This treatment may ultimately be used to sterilize acutely and chronically infected wounds unresponsive to antibiotics. PROPOSED COMMERCIAL APPLICATIONS: The commercial applications of this research is the use of PDT antimicrobial treatment with methylene blue and 664 nm laser light for the sterilization of antibiotic resistant acutely and chronically infected wounds found in debilitated and diabetic patients.